diff options
| -rw-r--r-- | changelog.d/6037.feature | 1 | ||||
| -rw-r--r-- | docs/sample_config.yaml | 26 | ||||
| -rw-r--r-- | synapse/config/saml2_config.py | 78 | ||||
| -rw-r--r-- | synapse/handlers/saml_handler.py | 105 | ||||
| -rw-r--r-- | synapse/rest/client/v1/login.py | 14 | ||||
| -rw-r--r-- | synapse/storage/registration.py | 41 | ||||
| -rw-r--r-- | synapse/storage/schema/delta/56/user_external_ids.sql | 24 |
7 files changed, 279 insertions, 10 deletions
diff --git a/changelog.d/6037.feature b/changelog.d/6037.feature new file mode 100644 index 0000000000..95d82bd4d8 --- /dev/null +++ b/changelog.d/6037.feature @@ -0,0 +1 @@ +Handle userid clashes when authenticating via SAML by appending an integer suffix. \ No newline at end of file diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml index 02b2332f7b..81f74b83ff 100644 --- a/docs/sample_config.yaml +++ b/docs/sample_config.yaml @@ -1169,6 +1169,32 @@ saml2_config: # #saml_session_lifetime: 5m + # The SAML attribute (after mapping via the attribute maps) to use to derive + # the Matrix ID from. 'uid' by default. + # + #mxid_source_attribute: displayName + + # The mapping system to use for mapping the saml attribute onto a matrix ID. + # Options include: + # * 'hexencode' (which maps unpermitted characters to '=xx') + # * 'dotreplace' (which replaces unpermitted characters with '.'). + # The default is 'hexencode'. + # + #mxid_mapping: dotreplace + + # In previous versions of synapse, the mapping from SAML attribute to MXID was + # always calculated dynamically rather than stored in a table. For backwards- + # compatibility, we will look for user_ids matching such a pattern before + # creating a new account. + # + # This setting controls the SAML attribute which will be used for this + # backwards-compatibility lookup. Typically it should be 'uid', but if the + # attribute maps are changed, it may be necessary to change it. + # + # The default is 'uid'. + # + #grandfathered_mxid_source_attribute: upn + # Enable CAS for registration and login. diff --git a/synapse/config/saml2_config.py b/synapse/config/saml2_config.py index c46ac087db..a022470702 100644 --- a/synapse/config/saml2_config.py +++ b/synapse/config/saml2_config.py @@ -12,7 +12,13 @@ # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. +import re + from synapse.python_dependencies import DependencyException, check_requirements +from synapse.types import ( + map_username_to_mxid_localpart, + mxid_localpart_allowed_characters, +) from ._base import Config, ConfigError @@ -36,6 +42,14 @@ class SAML2Config(Config): self.saml2_enabled = True + self.saml2_mxid_source_attribute = saml2_config.get( + "mxid_source_attribute", "uid" + ) + + self.saml2_grandfathered_mxid_source_attribute = saml2_config.get( + "grandfathered_mxid_source_attribute", "uid" + ) + import saml2.config self.saml2_sp_config = saml2.config.SPConfig() @@ -51,6 +65,12 @@ class SAML2Config(Config): saml2_config.get("saml_session_lifetime", "5m") ) + mapping = saml2_config.get("mxid_mapping", "hexencode") + try: + self.saml2_mxid_mapper = MXID_MAPPER_MAP[mapping] + except KeyError: + raise ConfigError("%s is not a known mxid_mapping" % (mapping,)) + def _default_saml_config_dict(self): import saml2 @@ -58,6 +78,13 @@ class SAML2Config(Config): if public_baseurl is None: raise ConfigError("saml2_config requires a public_baseurl to be set") + required_attributes = {"uid", self.saml2_mxid_source_attribute} + + optional_attributes = {"displayName"} + if self.saml2_grandfathered_mxid_source_attribute: + optional_attributes.add(self.saml2_grandfathered_mxid_source_attribute) + optional_attributes -= required_attributes + metadata_url = public_baseurl + "_matrix/saml2/metadata.xml" response_url = public_baseurl + "_matrix/saml2/authn_response" return { @@ -69,8 +96,9 @@ class SAML2Config(Config): (response_url, saml2.BINDING_HTTP_POST) ] }, - "required_attributes": ["uid"], - "optional_attributes": ["mail", "surname", "givenname"], + "required_attributes": list(required_attributes), + "optional_attributes": list(optional_attributes), + # "name_id_format": saml2.saml.NAMEID_FORMAT_PERSISTENT, } }, } @@ -146,6 +174,52 @@ class SAML2Config(Config): # The default is 5 minutes. # #saml_session_lifetime: 5m + + # The SAML attribute (after mapping via the attribute maps) to use to derive + # the Matrix ID from. 'uid' by default. + # + #mxid_source_attribute: displayName + + # The mapping system to use for mapping the saml attribute onto a matrix ID. + # Options include: + # * 'hexencode' (which maps unpermitted characters to '=xx') + # * 'dotreplace' (which replaces unpermitted characters with '.'). + # The default is 'hexencode'. + # + #mxid_mapping: dotreplace + + # In previous versions of synapse, the mapping from SAML attribute to MXID was + # always calculated dynamically rather than stored in a table. For backwards- + # compatibility, we will look for user_ids matching such a pattern before + # creating a new account. + # + # This setting controls the SAML attribute which will be used for this + # backwards-compatibility lookup. Typically it should be 'uid', but if the + # attribute maps are changed, it may be necessary to change it. + # + # The default is 'uid'. + # + #grandfathered_mxid_source_attribute: upn """ % { "config_dir_path": config_dir_path } + + +DOT_REPLACE_PATTERN = re.compile( + ("[^%s]" % (re.escape("".join(mxid_localpart_allowed_characters)),)) +) + + +def dot_replace_for_mxid(username: str) -> str: + username = username.lower() + username = DOT_REPLACE_PATTERN.sub(".", username) + + # regular mxids aren't allowed to start with an underscore either + username = re.sub("^_", "", username) + return username + + +MXID_MAPPER_MAP = { + "hexencode": map_username_to_mxid_localpart, + "dotreplace": dot_replace_for_mxid, +} diff --git a/synapse/handlers/saml_handler.py b/synapse/handlers/saml_handler.py index a1ce6929cf..f000d2a00f 100644 --- a/synapse/handlers/saml_handler.py +++ b/synapse/handlers/saml_handler.py @@ -21,6 +21,8 @@ from saml2.client import Saml2Client from synapse.api.errors import SynapseError from synapse.http.servlet import parse_string from synapse.rest.client.v1.login import SSOAuthHandler +from synapse.types import UserID, map_username_to_mxid_localpart +from synapse.util.async_helpers import Linearizer logger = logging.getLogger(__name__) @@ -29,12 +31,26 @@ class SamlHandler: def __init__(self, hs): self._saml_client = Saml2Client(hs.config.saml2_sp_config) self._sso_auth_handler = SSOAuthHandler(hs) + self._registration_handler = hs.get_registration_handler() + + self._clock = hs.get_clock() + self._datastore = hs.get_datastore() + self._hostname = hs.hostname + self._saml2_session_lifetime = hs.config.saml2_session_lifetime + self._mxid_source_attribute = hs.config.saml2_mxid_source_attribute + self._grandfathered_mxid_source_attribute = ( + hs.config.saml2_grandfathered_mxid_source_attribute + ) + self._mxid_mapper = hs.config.saml2_mxid_mapper + + # identifier for the external_ids table + self._auth_provider_id = "saml" # a map from saml session id to Saml2SessionData object self._outstanding_requests_dict = {} - self._clock = hs.get_clock() - self._saml2_session_lifetime = hs.config.saml2_session_lifetime + # a lock on the mappings + self._mapping_lock = Linearizer(name="saml_mapping", clock=self._clock) def handle_redirect_request(self, client_redirect_url): """Handle an incoming request to /login/sso/redirect @@ -60,7 +76,7 @@ class SamlHandler: # this shouldn't happen! raise Exception("prepare_for_authenticate didn't return a Location header") - def handle_saml_response(self, request): + async def handle_saml_response(self, request): """Handle an incoming request to /_matrix/saml2/authn_response Args: @@ -77,6 +93,10 @@ class SamlHandler: # the dict. self.expire_sessions() + user_id = await self._map_saml_response_to_user(resp_bytes) + self._sso_auth_handler.complete_sso_login(user_id, request, relay_state) + + async def _map_saml_response_to_user(self, resp_bytes): try: saml2_auth = self._saml_client.parse_authn_request_response( resp_bytes, @@ -91,18 +111,87 @@ class SamlHandler: logger.warning("SAML2 response was not signed") raise SynapseError(400, "SAML2 response was not signed") - if "uid" not in saml2_auth.ava: + logger.info("Got SAML2 reponse with attributes: %s", saml2_auth.ava) + + try: + remote_user_id = saml2_auth.ava["uid"][0] + except KeyError: logger.warning("SAML2 response lacks a 'uid' attestation") raise SynapseError(400, "uid not in SAML2 response") + try: + mxid_source = saml2_auth.ava[self._mxid_source_attribute][0] + except KeyError: + logger.warning( + "SAML2 response lacks a '%s' attestation", self._mxid_source_attribute + ) + raise SynapseError( + 400, "%s not in SAML2 response" % (self._mxid_source_attribute,) + ) + self._outstanding_requests_dict.pop(saml2_auth.in_response_to, None) - username = saml2_auth.ava["uid"][0] displayName = saml2_auth.ava.get("displayName", [None])[0] - return self._sso_auth_handler.on_successful_auth( - username, request, relay_state, user_display_name=displayName - ) + with (await self._mapping_lock.queue(self._auth_provider_id)): + # first of all, check if we already have a mapping for this user + logger.info( + "Looking for existing mapping for user %s:%s", + self._auth_provider_id, + remote_user_id, + ) + registered_user_id = await self._datastore.get_user_by_external_id( + self._auth_provider_id, remote_user_id + ) + if registered_user_id is not None: + logger.info("Found existing mapping %s", registered_user_id) + return registered_user_id + + # backwards-compatibility hack: see if there is an existing user with a + # suitable mapping from the uid + if ( + self._grandfathered_mxid_source_attribute + and self._grandfathered_mxid_source_attribute in saml2_auth.ava + ): + attrval = saml2_auth.ava[self._grandfathered_mxid_source_attribute][0] + user_id = UserID( + map_username_to_mxid_localpart(attrval), self._hostname + ).to_string() + logger.info( + "Looking for existing account based on mapped %s %s", + self._grandfathered_mxid_source_attribute, + user_id, + ) + + users = await self._datastore.get_users_by_id_case_insensitive(user_id) + if users: + registered_user_id = list(users.keys())[0] + logger.info("Grandfathering mapping to %s", registered_user_id) + await self._datastore.record_user_external_id( + self._auth_provider_id, remote_user_id, registered_user_id + ) + return registered_user_id + + # figure out a new mxid for this user + base_mxid_localpart = self._mxid_mapper(mxid_source) + + suffix = 0 + while True: + localpart = base_mxid_localpart + (str(suffix) if suffix else "") + if not await self._datastore.get_users_by_id_case_insensitive( + UserID(localpart, self._hostname).to_string() + ): + break + suffix += 1 + logger.info("Allocating mxid for new user with localpart %s", localpart) + + registered_user_id = await self._registration_handler.register_user( + localpart=localpart, default_display_name=displayName + ) + await self._datastore.record_user_external_id( + self._auth_provider_id, remote_user_id, registered_user_id + ) + return registered_user_id def expire_sessions(self): expire_before = self._clock.time_msec() - self._saml2_session_lifetime diff --git a/synapse/rest/client/v1/login.py b/synapse/rest/client/v1/login.py index 25a1b67092..9cddbc752a 100644 --- a/synapse/rest/client/v1/login.py +++ b/synapse/rest/client/v1/login.py @@ -29,6 +29,7 @@ from synapse.http.servlet import ( parse_json_object_from_request, parse_string, ) +from synapse.http.site import SynapseRequest from synapse.rest.client.v2_alpha._base import client_patterns from synapse.rest.well_known import WellKnownBuilder from synapse.types import UserID, map_username_to_mxid_localpart @@ -507,6 +508,19 @@ class SSOAuthHandler(object): localpart=localpart, default_display_name=user_display_name ) + self.complete_sso_login(registered_user_id, request, client_redirect_url) + + def complete_sso_login( + self, registered_user_id: str, request: SynapseRequest, client_redirect_url: str + ): + """Having figured out a mxid for this user, complete the HTTP request + + Args: + registered_user_id: + request: + client_redirect_url: + """ + login_token = self._macaroon_gen.generate_short_term_login_token( registered_user_id ) diff --git a/synapse/storage/registration.py b/synapse/storage/registration.py index 109052fa41..cc1b1b73c9 100644 --- a/synapse/storage/registration.py +++ b/synapse/storage/registration.py @@ -22,6 +22,7 @@ from six import iterkeys from six.moves import range from twisted.internet import defer +from twisted.internet.defer import Deferred from synapse.api.constants import UserTypes from synapse.api.errors import Codes, StoreError, ThreepidValidationError @@ -384,6 +385,26 @@ class RegistrationWorkerStore(SQLBaseStore): return self.runInteraction("get_users_by_id_case_insensitive", f) + async def get_user_by_external_id( + self, auth_provider: str, external_id: str + ) -> str: + """Look up a user by their external auth id + + Args: + auth_provider: identifier for the remote auth provider + external_id: id on that system + + Returns: + str|None: the mxid of the user, or None if they are not known + """ + return await self._simple_select_one_onecol( + table="user_external_ids", + keyvalues={"auth_provider": auth_provider, "external_id": external_id}, + retcol="user_id", + allow_none=True, + desc="get_user_by_external_id", + ) + @defer.inlineCallbacks def count_all_users(self): """Counts all users registered on the homeserver.""" @@ -999,6 +1020,26 @@ class RegistrationStore( self._invalidate_cache_and_stream(txn, self.get_user_by_id, (user_id,)) txn.call_after(self.is_guest.invalidate, (user_id,)) + def record_user_external_id( + self, auth_provider: str, external_id: str, user_id: str + ) -> Deferred: + """Record a mapping from an external user id to a mxid + + Args: + auth_provider: identifier for the remote auth provider + external_id: id on that system + user_id: complete mxid that it is mapped to + """ + return self._simple_insert( + table="user_external_ids", + values={ + "auth_provider": auth_provider, + "external_id": external_id, + "user_id": user_id, + }, + desc="record_user_external_id", + ) + def user_set_password_hash(self, user_id, password_hash): """ NB. This does *not* evict any cache because the one use for this diff --git a/synapse/storage/schema/delta/56/user_external_ids.sql b/synapse/storage/schema/delta/56/user_external_ids.sql new file mode 100644 index 0000000000..91390c4527 --- /dev/null +++ b/synapse/storage/schema/delta/56/user_external_ids.sql @@ -0,0 +1,24 @@ +/* Copyright 2019 The Matrix.org Foundation C.I.C. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +/* + * a table which records mappings from external auth providers to mxids + */ +CREATE TABLE IF NOT EXISTS user_external_ids ( + auth_provider TEXT NOT NULL, + external_id TEXT NOT NULL, + user_id TEXT NOT NULL, + UNIQUE (auth_provider, external_id) +); |